Implement getFieldList feature

src/Result/ResultSet.php

@@ -85,6 +85,32 @@ public function asArray():array {
 		);
 	}
 
+	/** @return array<string> */
+	public function getFieldList():array {
+		$fieldCount = $this->statement->columnCount();
+		$fieldList = [];
+		for($i = 0; $i < $fieldCount; $i++) {
+			$meta = $this->statement->getColumnMeta($i);
+			$name = $meta["name"] ?? null;
+			if(is_string($name)) {
+				$fieldList[] = $name;
+			}
+		}
+
+		if(!empty($fieldList)) {
+			return $fieldList;
+		}
+
+// Some drivers may not have the column meta - fetch the first row and reset.
+		$currentIteratorIndex = $this->iteratorIndex;
+		$this->rewind();
+		$row = $this->fetch();
+		$fieldList = $row?->getFieldList() ?? [];
+		$this->rewind();
+		$this->iteratorIndex = $currentIteratorIndex;
+		return $fieldList;
+	}
+
 	public function rewind():void {
 		$this->statement->execute();
 		$this->currentRow = null;

src/Result/Row.php

@@ -67,6 +67,11 @@ public function asArray():array {
 		return $this->data;
 	}
 
+	/** @return array<string> */
+	public function getFieldList():array {
+		return array_keys($this->data);
+	}
+
 	public function contains(string $name):bool {
 		return $this->__isset($name);
 	}

test/phpunit/Result/ResultSetTest.php

@@ -88,6 +88,44 @@ public function testCountTwice() {
 		self::assertCount($count, $resultSet);
 	}
 
+	public function testGetFieldList() {
+		$resultSet = new ResultSet($this->getStatementMock());
+		self::assertSame(
+			["id", "name", "timestamp", "date"],
+			$resultSet->getFieldList()
+		);
+	}
+
+	public function testGetFieldListFallbackToFirstRow() {
+		$resultSet = new ResultSet($this->getStatementMock(false));
+		self::assertSame(
+			["id", "name", "timestamp", "date"],
+			$resultSet->getFieldList()
+		);
+	}
+
+	public function testGetFieldListNoRows() {
+		$statement = $this->createMock(PDOStatement::class);
+		$statement->method("fetch")->willReturn(null);
+		$statement->method("execute")->willReturn(true);
+		$statement->method("columnCount")->willReturn(0);
+		$resultSet = new ResultSet($statement);
+
+		self::assertSame([], $resultSet->getFieldList());
+	}
+
+	public function testGetFieldListMidIteration() {
+		$resultSet = new ResultSet($this->getStatementMock());
+		$resultSet->rewind();
+		$resultSet->next();
+
+		self::assertSame(
+			["id", "name", "timestamp", "date"],
+			$resultSet->getFieldList()
+		);
+		self::assertEquals(2, $resultSet->current()->id);
+	}
+
 	public function testAccessByRowIndex() {
 		$resultSet = new ResultSet($this->getStatementMock());
 
@@ -137,12 +175,25 @@ public function testAsDateTime() {
 		self::assertEquals("1988-04-05 17:24", $row->getDateTime("timestamp")->format("Y-m-d H:i"));
 	}
 
-	private function getStatementMock():PDOStatement {
+	private function getStatementMock(bool $withMetadata = true):PDOStatement {
 		$statement = $this->createMock(PDOStatement::class);
 		$statement->method("fetch")
 			->will(self::returnCallback([$this, "getNextFakeData"]));
 		$statement->method("execute")
 			->willReturnCallback([$this, "rewindFakeData"]);
+		if($withMetadata) {
+			$statement->method("columnCount")
+				->willReturn(count(self::FAKE_DATA[0]));
+			$statement->method("getColumnMeta")
+				->willReturnCallback(function(int $index):array {
+					$name = array_keys(self::FAKE_DATA[0])[$index] ?? null;
+					return ["name" => $name];
+				});
+		}
+		else {
+			$statement->method("columnCount")
+				->willReturn(0);
+		}
 
 		return $statement;
 	}

test/phpunit/Result/RowTest.php

@@ -56,6 +56,19 @@ public function testContains() {
 		self::assertFalse($row->contains("col2"));
 	}
 
+	public function testGetFieldList() {
+		$row = new Row([
+			"id" => 123,
+			"name" => "Example",
+			"enabled" => 1,
+		]);
+
+		self::assertSame(
+			["id", "name", "enabled"],
+			$row->getFieldList()
+		);
+	}
+
 	/** @dataProvider data_getTestRow */
 	public function testIteration(array $data) {
 		$row = new Row($data);